Deletion of _KEVA_NS_ is not allowed.

src/wallet/rpckeva.cpp

@@ -327,6 +327,10 @@ UniValue keva_delete(const JSONRPCRequest& request)
     throw JSONRPCError (RPC_INVALID_PARAMETER, "the key is too long");
   }
 
+  if (keyStr == CKevaScript::KEVA_DISPLAY_NAME_KEY) {
+    throw JSONRPCError (RPC_INVALID_PARAMETER, "_KEVA_NS_ cannot be deleted");
+  }
+
   bool hasKey = false;
   CKevaData data;
   {

test/functional/feature_keva.py

@@ -282,6 +282,13 @@ class KevaTest(BitcoinTestFramework):
         response = self.nodes[0].keva_get(namespaceId, keyToDelete)
         assert(response['value'] == newValue)
 
+        try:
+            self.nodes[0].keva_delete(namespaceId, "_KEVA_NS_")
+        except JSONRPCException:
+            pass
+        else:
+            raise Exception("Should not be able to delete _KEVA_NS_")
+
         self.log.info("Test disconnecting blocks")
         self.run_test_disconnect_block()